Organic light emitting display device and method for manufacturing the same

ABSTRACT

The organic light emitting display device includes a flexible substrate, a thin-film transistor on the flexible substrate, a first anode on the thin-film transistor, a second anode on the same plane with the first anode and spaced apart from the first anode so as to surround the first anode, an organic light emitting layer on the first anode and the second anode, and a cathode on the organic light emitting layer. The second anode includes an opening where the first anode is encompassed therein. The shape of the first anode and the second anode and arrangement thereof reduces a segment length of an anode in a bending direction of the organic light emitting display device, and, thus, occurrence of cracks in the anode can be minimized.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority of Korean Patent Application No.10-2013-0130882 filed on Oct. 31, 2013, in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein byreference.

BACKGROUND

1. Field of Technology

The present disclosure relates to an organic light emitting displaydevice and a method for improving flexibility of the organic lightemitting display device. More particularly, the present disclosurerelates to an organic light emitting display device and method forminimizing crack occurrences in an active area by reducing the strain onan organic light emitting element from the bending stress.

2. Description of the Related Art

In recent years, flexible display devices manufactured to display animage even when bent like paper by forming a display unit and a wire ona substrate exhibiting flexibility, such as a flexible material (i.e., aplastic), have received attention as next-generation display devices.

Flexible display devices have been widely used in the field ofapplications spanning from monitors of computers and televisions (TVs)to personal portable equipment, and research on flexible display deviceshaving a large display area and a smaller volume and weight has beenconducted. Especially, since an organic light emitting display devicedoes not need a separate light source unlike a liquid crystal displaydevice, it is possible to implement the organic light emitting displaydevice at a relatively thin thickness. Accordingly, it has beenattempted to manufacture the organic light-emitting display device asthe flexible display device.

SUMMARY

In a rectangular pixel area structure widely used in a present organiclight emitting display device, a shape of an anode is the same as ashape of the pixel area. The anode in a rectangular shape is vulnerableto a tensile force and a compressive force in bending of the organiclight emitting display device. Further, a transparent conductive oxideused as the anode of the organic light emitting display device has lowerflexibility as compared with other materials included in an active areawhere images are displayed. Thus, cracks may occur in the anode whenbending the active area where the organic light emitting display deviceis disposed. With cracks in the anode, parts of the anode may be unableto receive the signal from the thin-film transistor. This may result inreduced luminance in the organic light emitting display element. Thus,in order to minimize non-uniformity or reduction in luminance due tocracks in an anode, the present inventors invented a new pixelconfiguration and a new anode structure for the corresponding pixelconfiguration to make the organic light emitting element withstandbetter against the bending stress.

Thus, an object of the present disclosure is to provide an organic lightemitting display device for minimizing crack occurrences in an activearea in bending of the organic light emitting display device, and amethod for reducing the strain on the organic light emitting elementfrom the bending stress.

The objects of the present disclosure are not limited to theaforementioned objects, and other objects, which are not mentionedabove, will be apparent to those skilled in the art from the followingdescription.

According to an exemplary embodiment of the present disclosure, there isprovided a flexible organic light emitting display device having aplurality of pixels. At least one of the pixels comprises at least onethin-film transistor, a first anode on the thin-film transistor, asecond anode on the thin-film transistor, an organic light emittinglayer on the first anode and the second anode and a cathode on theorganic light emitting layer. The second anode has an opening where thefirst anode is encompassed therein. A shape of the first anode and thesecond anode and arrangement thereof reduce a segment length of an anodein a bending direction of the flexible organic light emitting displaydevice. Thus, occurrence of cracks in the first anode and the secondanode can be minimized. Further, it is possible to solve non-uniformityor reduction in luminance of the flexible organic light emitting displaydevice caused by cracks in the first anode and the second anode.

In some embodiments, a shape of the opening in the second anodecorresponds to a shape of the first anode.

In some embodiments, the first anode has a rectangular shape.

In some embodiments, corners of the first anode and the second anode arerounded.

In some embodiments, the one pixel includes at least one thin-filmtransistor that is connected to both the first anode and the secondanode.

In some embodiments, each of the first anode and the second anode of thepixel are connected to a discrete thin-film transistor.

In some embodiments, the flexible organic light emitting display devicefurther comprises a bridge electrode that connects the first anode andthe second anode.

In some embodiments, the at least one of the first anode and the secondanode has a division gap formed therein in a direction perpendicular toa bending direction of a flexible substrate.

According to an exemplary embodiment of the present disclosure, there isprovided an organic light emitting display device. The organic lightemitting display device comprises a flexible substrate including abending area and a thin-film transistor and an organic light emittingelement in the bending area of the flexible substrate, wherein theorganic light emitting element includes a first light emitting area, asecond light emitting area spaced apart from the first light emittingarea so as to surround the first light emitting area, and a third lightemitting area spaced apart from the second light emitting area so as tosurround the second light emitting area. Therefore, a shape andarrangement of the light emitting areas may provide a shape andarrangement of an anode by which occurrence of cracks in the anode canbe minimized.

In some embodiments, the first light emitting area, the second lightemitting area and the third light emitting area are separated by a banklayer.

In some embodiments, each organic light emitting layer in each of thefirst light emitting area, the second light emitting area and the thirdlight emitting area emits light of substantially the same spectral coloror white light.

In some embodiments, each of the organic light emitting layers in eachof the light emitting areas emits the white light, and each of the lightemitting areas includes a color filter configured to filter the whitelight from the respective organic light emitting layer.

In some embodiments, the each of the first light emitting area, thesecond light emitting area and the third light emitting area emits lightof different color from one another.

In some embodiments, the light of different colors emitted from thefirst light emitting area, the second light emitting area and the thirdlight emitting area includes red color, green color and blue color.

In some embodiments, the third light emitting area is a blue lightemitting area.

In some embodiments, at least one of the first light emitting area, thesecond light emitting area, and the third light emitting area is dividedinto multiple parts.

According to an exemplary embodiment of the present disclosure, there isprovided a method of manufacturing an organic light emitting displaydevice. The method comprises forming a thin-film transistor on aflexible substrate, forming an anode material layer on the thin-filmtransistor, patterning the anode material layer into a first anode, asecond anode spaced apart from the first anode and a third anode spacedapart from the second anode such that the first anode is surrounded bythe second anode, and the second anode is surrounded by the third anode,forming an organic light emitting layer on the first anode, the secondanode, and the third anode and forming a cathode on the organic lightemitting layer. A shape of the anodes formed by the above-describedmethod have an effect of dispersing a force received by an organic lightemitting element in a bending direction toward the first anode, thesecond anode, and the third anode. Therefore, it is possible to minimizea force received by the anodes of the organic light emitting element dueto bending and occurrence of cracks in the anodes.

In some embodiments, the organic light emitting layer includes a firstorganic light emitting layer having the same shape as the first anodeand formed thereon, a second organic light emitting layer having thesame shape as the second anode and formed thereon, and a third organiclight emitting layer having the same shape as the third anode and formedthereon.

In some embodiments, the first organic layer having the same shape asthe first anode is spaced apart from the second organic light emittinglayer having the same shape as the second anode, and the second organiclight emitting layer is spaced apart from the third organic lightemitting layer having the same shape as the third anode.

In some embodiments, the conductive layer is patterned to form a firstbridge and a second bridge, the first bridge connecting the first anodeand the second anode, and the second bridge connecting the second anodeand the third anode.

In some embodiments, the conductive layer is patterned to form adivision gap such that at least one of the first anode, the second anodeand the third anode is divided into multiple parts.

Details of other exemplary embodiments are included in the detaileddescription and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and other advantages of thepresent disclosure will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1A is a schematic cross-sectional view illustrating a shape of ananode and a bank layer employed in an organic light emitting displaydevice according to one embodiment of the present disclosure;

FIG. 1B is a cross-sectional view taken along a line Ib-Ib′ of FIG. 1Ato explain a driving method of the organic light emitting display deviceaccording to one embodiment;

FIG. 1C is a cross-sectional view taken along the line Ib-Ib′ of FIG. 1Ato explain a driving method of the organic light emitting display deviceaccording to another embodiment;

FIG. 2A is a schematic plane view illustrating a shape of an anode and abank layer for explaining a bridge electrode employed in an organiclight emitting display device according to one embodiment;

FIG. 2B is a cross-sectional view of the organic light emitting displaydevice taken along a line IIb-IIb′ of FIG. 2A according to oneembodiment;

FIG. 3A is a schematic perspective view provided for explaining abending direction of a bent organic light emitting display deviceaccording to one embodiment;

FIG. 3B is a schematic plane view illustrating a shape of an anode and abank layer in a bent organic light emitting display device according toone embodiment;

FIG. 4A and FIG. 4B are schematic plane views of a pixel area and ananode for explaining effects of an organic light emitting display deviceaccording to various embodiments;

FIG. 5A is a schematic plane view illustrating a light emitting areaemployed in an organic light emitting display device according to oneembodiment;

FIG. 5B is a cross-sectional view taken along a line Vb-Vb′ of FIG. 5Ato explain a driving method of the organic light emitting display deviceaccording to one embodiment;

FIG. 5C is a cross-sectional view taken along the line Vb-Vb′ of FIG. 5Ato explain a driving method of the organic light emitting display deviceaccording to another embodiment;

FIG. 6 is a flowchart provided for explaining a method for reducing aforce received by an organic light emitting element due to bending ofthe organic light emitting element according to one exemplaryembodiment; and

FIGS. 7A, 7B, and FIG. 7C are cross-sectional views of respectiveprocesses provided for explaining a method for reducing a strain on anorganic light emitting element from a bending stress according to oneembodiment.

DETAILED DESCRIPTION

Various advantages and features of the present invention and methodsaccomplishing thereof will become apparent from the followingdescription of embodiments with reference to the accompanying drawings.However, the present invention is not limited to exemplary embodimentdisclosed herein but will be implemented in various forms. The exemplaryembodiments are provided by way of example only so that a person ofordinary skilled in the art can fully understand the disclosures of thepresent invention and the scope of the present invention. Therefore, thepresent invention will be defined only by the scope of the appendedclaims.

Indicating that elements or layers are “on” other elements or layersinclude both a case in which the corresponding elements are just aboveother elements and a case in which the corresponding elements areintervened with other layers or elements.

Although first, second, and the like are used in order to describevarious components, the components are not limited by the terms. Theabove terms are used only to differentiate one component from the othercomponent. Therefore, a first component mentioned below may be a secondcomponent within the technical spirit of the present invention.

The same reference numerals indicate the same elements throughout thespecification.

In the drawings, size and thickness of each element are arbitrarilyillustrated for convenience of description, and the present invention isnot necessarily limited to those illustrated in the drawings.

In the embodiments described herein, a flexible display apparatus meansa display apparatus having flexibility, and is used as the same meaningas a bendable display apparatus, a rollable display apparatus, anunbreakable display apparatus, a foldable display apparatus, a twistabledisplay apparatus, a stretchable display apparatus, a wrinkable displayapparatus, and the like. In the embodiments described herein, theflexible organic light emitting display apparatus means an organic lightemitting display apparatus among various flexible display devices.

The components of various embodiments can be partially or entirelybonded to or combined with each other and can be interlocked andoperated in technically various ways as can be fully understood by anordinary person skilled in the art, and the embodiments can be carriedout independently of or in association with each other.

Hereinafter, various embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings.

FIG. 1A is a schematic cross-sectional view illustrating a shape of ananode and a bank layer employed in an organic light emitting displaydevice according to one embodiment. In FIG. 1A, among various elementsof an organic light emitting display device, only an anode 140A and abank layer 170A are illustrated for convenience of explanation, and theanode 140A is illustrated by a solid line and the bank layer 170A isillustrated by a dotted line.

The anode 140A includes a conductive material having a high workfunction in order to supply a hole to an organic light emitting layer.The anode 140A may be formed of a transparent conductive layer having ahigh work function. The transparent conductive layer includes atransparent conductive oxide (TCO) such as an indium tin oxide (ITO), anindium zinc oxide (IZO), an indium tin zinc oxide (ITZO), a zinc oxide,a tin oxide.

The anode 140A includes a first anode 141A and a second anode 142Aformed on the same plane. The second anode 142A is spaced apart from thefirst anode 141A so as to surround the first anode 141A. That is, thesecond anode 142A has an opening in the middle, and the first anode141A, which is on the same plane as the second anode 142A, is formedwithin the opening of the second anode 142A. A space may exist betweenthe second anode 142A and the first anode 141A surrounded by the secondanode 142A.

As shown in the FIG. 1A, the first anode 141A may be formed in arectangular shape (e.g., diamond), and the second anode 142A may beformed in a shape corresponding to the shape of the first anode 141A. Inthis example, the outline shape of the first anode 141A is substantiallyidentical with the outline shape of the second anode 142A. Therefore,the shape formed by the second anode 142A is also a rectangular shape.Although FIG. 1A illustrates the first anode 141A and the second anode142A having a rectangular shape, the shapes of the first anode 141A andthe second anode 142A are not limited thereto and may be anotherpolygonal shape or a circular shape.

The bank layer 170A includes a first bank layer 171A that partitions thefirst anode 141A and the second anode 142A and a second bank layer 172Athat surrounds an outer portion of the second anode 142A. The bank layer170A is formed on a contact hole where each of the first anode 141A andthe second anode 142A is electrically connected with a structure thatapplies a voltage to the first anode 141A and the second anode 142A. Thebank layer 170A opens a part of the first anode 141A and a part of thesecond anode 142A.

The transparent conductive oxide contained in the anode has relativelylow flexibility as compared to the material for forming the organiclight emitting layer and the material for forming the cathode.Therefore, in bending the organic light emitting display device, cracksare highly likely to occur in the anode as compared with othercomponents of the organic light emitting display device. Further, whenan anode used in an organic light emitting display device is formed in arectangular shape, the anode may be vulnerable to a tensile force or acompressive force caused by bending, depending on its orientationrelative to the bending direction. The longer the continuous length ofthe anode aligned to the bending direction, the higher the chances ofcrack generation in the anode.

If cracks occur in the anode, a signal may not be transmitted to theanode, and thereby the organic light emitting display device cannot beoperated normally. Therefore, the organic light emitting display devicemay have a non-uniform luminance or a reduced luminance.

In an organic light emitting display device according to one embodiment,in order to reduce the possibility of occurrence of cracks in an anode,there is provided an anode structure in which a segment length of ananode along a bending direction is reduced. The anode 140A is dividedinto the first anode 141A and the second anode 142A. In particular, thesecond anode 142A is spaced apart from the first anode 141A so as tosurround the first anode 141A. In this way, the segment length of theanode 140A in the bending direction can be reduced, thereby reducing thepossibility of occurrence of cracks in the anode 140A. Here, a segmentlength of an anode in a bending direction means a unit length of ananode extending in a bending direction.

Corner portions of the first anode 141A and the second anode 142A may beformed into a round shape. With the round shape of the corner portions,the bending stress, which may be concentrated on the corner portions ofthe first anode 141A and the second anode 142A can be spread out to awider portion of the respective anodes. In this way, the possibility ofcrack generation at the corners of the first anode 141A and the secondanode 142A can be reduced.

Although FIG. 1A illustrates that the anode 140A includes the firstanode 141A and the second anode 142A, the number of sub-anodesconstituting the anode 140A is not limited. For example, the anode 140Amay further include a third anode which is spaced apart from the secondanode 142A so as to surround the second anode 142A. The third anode maybe formed along the shape of the second anode 142A. Also, the anode 140Amay further include a fourth anode which is spaced apart from the thirdanode so as to surround the third anode.

FIG. 1B is a cross-sectional view taken along a line Ib-Ib′ of FIG. 1Ato explain a driving method of the organic light emitting display deviceaccording to one embodiment. Referring to FIG. 1B, an organic lightemitting display device 100B includes a flexible substrate 110B, abuffer layer 131B, a thin-film transistor 120B, a gate insulating layer132B, an interlayer insulating layer 133B, an overcoating layer 134B, acontact portion 129B, an anode 140B, an organic light emitting layer150B, a cathode 160B, and a bank layer 170B.

An organic light emitting element including the anode 140B, the organiclight emitting layer 150B and the cathode 160B is formed on theovercoating layer 134B.

The organic light emitting layer 150B is formed on the anode 140B openedby the bank layer 170B. A first organic light emitting layer 151B isformed on a first anode 141B opened by a first bank layer 171B, and asecond organic light emitting layer 152B is formed on a second anode142B opened by a second bank layer 172B. As illustrated in FIG. 1B, thefirst organic light emitting layer 151B and the second organic lightemitting layer 152B are formed so as to be separated from each other.Each of the first organic light emitting layer 151B and the secondorganic light emitting layer 152B is an organic light emitting layerthat emits any one of red, green, blue, and white light. Colors of lightemitted from the first organic light emitting layer 151B and colors oflight emitted from the second organic light emitting layer 152B may bethe same or different.

The cathode 160B is formed on the organic light emitting layer 150B. Thecathode 160B needs to supply electrons, and, thus, the cathode 160B isformed of a conductive material having a low work function. The cathode160B is connected with a separate wiring from the anode 140A and appliesa common voltage to all pixel areas and all sub-pixel areas in an activearea. Therefore, in some embodiments, the cathode 160B may not bepatterned and may be formed as continuous layer on the organic lightemitting layer 150B. If the organic light emitting display device 100Baccording to one embodiment is a top-emission type organic lightemitting display device, the cathode 160B is formed to a very smallthickness and can be substantially transparent.

If the organic light emitting display device 100B according to oneembodiment is a top-emission type organic light emitting display device,the anode 140B includes a reflective layer formed under a transparentconductive layer. A light emitted toward the reflective layer isreflected and exits toward cathode 160B. Accordingly, the reflectivelayer should be formed of a conductive layer having a sufficiently highreflectivity. Examples of the material satisfying the above mentionedrequirements include, for example, silver (Ag), nickel (Ni), gold (Au),platinum (Pt), aluminum (Al), copper (Cu), andmolybdenum/aluminum-neodymium (Mo/AlNd).

The thin-film transistor 120B is formed on the buffer layer 131B. Thethin-film transistor 120B includes an active layer 121B, a gateelectrode 122B, a source electrode 123B, and a drain electrode 124B. Inthe embodiments herein, among various thin-film transistors which may beincluded in the organic light emitting display device 100B, only thedriving thin-film transistor 120B is illustrated for convenience ofexplanation. Further, in the specification, the thin-film transistor120B is illustrated as having a coplanar structure, but a thin-filmtransistor having an inverted staggered structure may be used.

The active layer 121B, in which a channel of the thin-film transistor120B is formed, is formed to be in contact with the buffer layer 131B.If the buffer layer 131B is not formed, the active layer 121B isdirectly formed on the flexible substrate 110B. On the active layer121B, the gate insulating layer 132B is formed in order to insulate theactive layer 121B and the gate electrode 122B. On the gate insulatinglayer 132B, the gate electrode 122B is formed. On the gate electrode122B, the interlayer insulating layer 133B is formed. The interlayerinsulating layer 133B is formed on the entire surface of the flexiblesubstrate 110B and includes a contact hole that opens a part of theactive layer 121B. On the gate insulating layer 132B, the sourceelectrode 123B and the drain electrode 124B are formed. The sourceelectrode 123B is electrically connected with the active layer 121B viathe contact hole.

The contact portion 129B is formed on the interlayer insulating layer133B. The contact portion 129B is configured to electrically connect thefirst anode 141B with the thin-film transistor 120B. Although notillustrated in the cross-sectional view of FIG. 1B, the contact portion129B may be in contact with the source electrode 123B of the thin-filmtransistor 120B, which may be on the plane.

The overcoating layer 134B is formed on the thin-film transistor 120Band the contact portion 129B. The overcoating layer 134B can serve as aplanarization film and provides a planar surface over the thin-filmtransistor 120. In this setting, the overcoating layer 134B includes acontact hole that allows the source electrode 123B or the drainelectrode 124B to be exposed and a contact hole that opens a part of thecontact portion 129B. Since FIG. 1B illustrates a case where thethin-film transistor 120B is a n-type thin-film transistor, theovercoating layer 134B includes a contact hole that allows the sourceelectrode 123B to be exposed.

In some embodiments, the voltage applied to the first anode 141B and thesecond anode 142B may be the same. Referring to FIG. 1B, the secondanode 142B is electrically connected with the source electrode 123B ofthe thin-film transistor 120B via the contact hole of the overcoatinglayer 134B. The first anode 141B is electrically connected with thecontact portion 129B via the contact hole of the overcoating layer 134B.As described above, the contact portion 129B may be connected with thesource electrode 123B of the thin-film transistor 120B so that the firstanode 141B and the second anode 142B are applied with the same voltagefrom the source electrode 123B of the thin-film transistor 120B.

In some embodiments, the first anode 141B and the second anode 142B arespaced apart from each other and partitioned from each other by the banklayer 170B. In this case, the organic light emitting element includesone light emitting area defined by the first anode 141B, the firstorganic light emitting layer 151B and the cathode 160B, and the anotherlight emitting area defined by the second anode 142B, the second organiclight emitting layer 152B and the cathode 160B. In the embodiments wherethe same voltage is applied to the first anode 141B and the second anode142B, the color of light emitted from the first organic light emittinglayer 151B may be the same as a color of light emitted from the secondlight emitting layer 152B. Providing two light emitting areas in asub-pixel area may be advantageous in terms of driving and design of anorganic light emitting element. For instance, one light emitting areacan be driven independently from the other light emitting area, andfurther, serve as a backup light emitting area even when the other lightemitting area fails to operate due to the bending stress.

The first organic light emitting layer 151B and the second organic lightemitting layer 152B may emit the same color of light. It should be notedthat, in the present disclosure, the same colored light may indicatethat the wavelengths of the light being encompassed within apredetermined range of wavelengths defining a spectral color in thevisible light spectrum. Further, each organic light emitting layer(e.g., the first organic light emitting layer 151B and the secondorganic light emitting layer 152B) may be configured to emit light thatis generated by a combination of multiple spectral colors, sometimesreferred to as white light. If the first organic light emitting layer151B and the second organic light emitting layer 152B emit white light,the first organic light emitting layer 151B and the second organic lightemitting layer 152B may not be separated from each other and may beformed to be connected to each other. If the first organic lightemitting layer 151B and the second organic light emitting layer 152B areformed so as to emit white light, a color filter may be used together.

FIG. 1C is a cross-sectional view taken along the line Ib-Ib′ of FIG. 1Aaccording to one embodiment. FIG. 1C is used to explain a driving methodof the organic light emitting display device different from the drivingmethod of FIG. 1B. An organic light emitting display device 100C of FIG.1C is different from the organic light emitting display device 100Billustrated in FIG. 1B only in that a discrete thin-film transistor 120Cand 120C′ are employed in a pixel.

In this embodiment, thin-film transistors 120C and 120C′ correspondingto a first anode 141C and a second anode 142C, respectively, are formedon a buffer layer 131C. The first anode 141C is electrically connectedwith a source electrode 123C′ of the thin-film transistor 120C′, and thesecond anode 142C is electrically connected with a source electrode 123Cof the thin-film transistor 120C. Therefore, different voltages may beapplied to the first anode 141C and the second anode 142C from thethin-film transistors 120C and 120C′, respectively.

Since different voltages may be applied to the first anode 141C and thesecond anode 142C, the first light emitting area, which is formed by thefirst anode 141C, and the second light emitting area, which is formed bythe second anode 142C, can be driven independently from each other. Inthis case, the first organic light emitting layer 151C on the firstanode 141C and the second organic light emitting layer 152C on thesecond anode 142C can emit different color of light so that each lightemitting area can serve as an individual sub-pixel area.

Alternatively, in some embodiments, the first organic light emittinglayer 151C and the second organic light emitting layer 152C can beconnected to each other, and the first organic light emitting layer 151Cand the second organic light emitting layer 152C may emit light within acertain limited range of wavelengths or the white light. In such cases,each sub-pixel area can be defined by a color filter.

FIG. 2A is a schematic plane view illustrating a shape of an anode and abank layer for explaining a bridge electrode employed in an organiclight emitting display device according to one embodiment. FIG. 2B is across-sectional view of the organic light emitting display device takenalong a line IIb-IIb′ of FIG. 2A according to one embodiment. Referringto FIG. 2A and FIG. 2B, an organic light emitting display device 200Aincludes a flexible substrate 210A, a buffer layer 231A, a thin-filmtransistor 220A, a gate insulating layer 232A, an interlayer insulatinglayer 233A, an overcoating layer 234A, an anode 240A, an organic lightemitting layer 250A, a cathode 260A, and a bank layer 270A. In thisembodiment, the anode 240A includes a bridge electrode 249A thatconnects the first anode 241A and the second anode 142A. Unlike thecontact portion 129B employed in the organic light emitting displaydevice 100B of FIG. 1B, the bridge electrode 249A shown in FIG. 2B canbe in the same plane level as the first anode 241A and the second anode242A.

Accordingly, the anode 240A includes a first anode 241A, a second anode242A and a bridge electrode 249A. The bridge electrode 249A connectingthe first anode 241A with the second anode 242A can be formedsimultaneously with the first anode 241A and the second anode 242A inthe same material. Since the first anode 241A and the second anode 242Aare electrically connected by the bridge electrode 249A, only one of thefirst anode 241A or the second anode 242A can be connected to thethin-film transistor 220A. In FIG. 2A and FIG. 2B, the second anode242A, which is surrounding the first anode 241A, is connected with thethin-film transistor 220A. However, the configuration is not limited asthereto, and an anode that is surrounded by another anode can be the onethat is connected to the thin-film transistor. Since the same voltage isapplied to the first anode 241A and the second anode 242A, two lightemitting areas can be defined to one sub-pixel area by combining thecolor of light emitted from the first organic light emitting layer 251Awith the color of light emitted from the second organic light emittinglayer 252A.

FIG. 3A is a schematic perspective view of an organic light emittingdisplay device bent in a bending direction, according to one embodiment.In FIG. 3A, among various elements of a bent organic light emittingdisplay device, only a flexible substrate 310A, a first anode 341A, anda second anode 342A are illustrated for convenience of explanation.

The flexible substrate 310A can be bent in upward or downward direction.Prior to bending of the flexible substrate 310A, any two points P and Qon the flexible substrate 310A (e.g., the points along the side line ofthe flexible substrate 310A) in a plane within an XYZ orthogonalcoordinate system. A direction in which the side line connecting the twopoints P and Q in the flexible substrate 310A may be defined as theX-axis and a straight line orthogonal to the line connecting the twopoints P and Q in the flexible substrate 310A may be defined as theY-axis, which together define the XY plane. A line normal to the XYplane formed by the X-axis and the Y-axis in the flexible substrate 310Amay be defined as the Z-axis of the XYZ orthogonal coordinate system.When the flexible substrate 310A is bent as illustrated in FIG. 3A, atangent vector of the curvature can be defined as the bending direction.That is, a direction indicated by the tangent vector of the curvature ofthe XY plane between the two points P and Q can be defined as thebending direction of the flexible substrate 310A. In the embodiment ofthe flexible substrate 310A illustrated in FIG. 3A, a bending directionof the flexible substrate 310A can be a direction of a unit vector (1,0).

FIG. 3B is a schematic plane view illustrating a shape of an anode and abank layer, which may be used in an embodiment of the organic lightemitting display device. In FIG. 3B, the anode 340A is illustrated by asolid line and the bank layer 370A is illustrated by a dotted line.While the anode 340A and the bank layer 370A are illustrated in a planarform for convenience of explanation, it should be understood that theanode 340A and the bank layer 370A can be positioned on the flexiblesubstrate 310A that is bent in the bending direction.

As shown in FIG. 3B, the anode 340A includes a first anode 341A and asecond anode 342A. In some embodiments, at least one of a first anode341A and a second anode 342A may be further divided into multiple parts.Using this approach, the segment length of the respective anode beinglinearly aligned to the bending direction can be reduced to a greaterextent, making the anode to withstand better against the bending stress.

By way of example, the anode 342A can be split into two parts by a setof division gaps formed at the vertexes of the rectangular shaped anode342A as shown in FIG. 3B. In this example, the division gaps are formedat the two far end corners of the anode 342A, which are positioned awayfrom the central axis of the anode 340A parallel to the bendingdirection. The straight line between the two corners with the divisiongap is in an oblique angle or substantially perpendicular to the bendingdirection (denoted by the arrow) of the flexible substrate 310A. Eachsplit part of the anode 342A is on one side of the straight line betweenthe division gaps extending in an oblique angle or perpendicular to thebending direction of the flexible substrate 310A.

When the second anode 342A having a rectangular shape, for instance adiamond shape, is bent, the bend stress tends to concentrated at thecorners of the second anode 342A and initiate cracks therefrom. However,the division gap provided at the corners of the second anode 342Afacilitates reduction of bend stress at those stress points.

Each of the first anode 341A and the divided second anodes 342A iselectrically connected with a thin-film transistor or a contact portionvia a contact hole and applied with a voltage. Since the second anode342A is divided, the bank layer 370A is positioned between the firstanode 341A and the second anode 342A and between the divided secondanodes 342A and further includes a third bank layer 373A that connects afirst bank layer 371A and a second bank layer 372A. Also, each of thefirst anodes 341A and the second anode 342A may be electricallyconnected using the bridge electrode as illustrated in FIG. 2A.

Although FIG. 3B illustrates that only the second anode 342A has thedivision gap, the first anode 341A may also be divided into multipleparts. For instance, a division gap may be formed across the first anode341A in an orthogonal angle or substantially perpendicular to thebending direction of the flexible substrate 310A. In some embodiments,both the first anode 341A and the second anode 342A may be divided intomultiple parts.

In FIG. 3B, the division gaps of the second anode 342A are illustratedas being positioned at the corners away from the axis of the anode 342Aparallel to the bending direction. However, in some embodiments, thedivision gaps may be provided at the corners along the axis of the anode342, which may be substantially parallel to the bending direction.Likewise, the division gap for dividing the first anode 341A may beextended substantially parallel to the bending direction of the flexiblesubstrate 310A.

FIG. 4A and FIG. 4B are schematic plane views of various pixel areaconfigurations and anode configurations according to one embodiment.When an anode is bent in a specific direction, a tensile force and acompressive force received by the anode due to bending in the specificdirection are proportional to a segment length of the anode in thespecific direction. If a segment length of the anode in the bendingdirection of the anode is longer, a strain on the anode from the bendingstress is increased, and as the strain on the anode is increased, thepossibility of occurrence of cracks in the anode is also increased.Therefore, the possibility of occurrence of cracks in an anode in aspecific bending direction is proportional to the maximum value of asegment length of the anode in the bending direction of the anode, andthe possibility of occurrence of cracks in an anode in various bendingdirections is proportional to the average of the maximum values ofsegment lengths of the anode in the various bending directions. Thus,maximum values of segment lengths of the anodes are calculated asillustrated in FIGS. 4A (i), (ii), (iii), and (iv) in angular directionsof 0 degree, 45 degrees, and 90 degrees, and also calculated the averagethereof. Details are as follows.

TABLE 1 Angle (based on X-axis) (i) (ii) (iii) (iv) 0 1 1.414 0.3920.392 45 1.414 1.333 1.110 1.110 90 2 2.828 0.785 0.785 Average 1.4711.858 0.762 0.762

As illustrated in Table 1, it can be seen that in the case illustratedin FIG. 4A(ii), the average of the maximum values of segment lengths ofthe anode in the various bending directions is increased as comparedwith the case illustrated in FIG. 4A(i). However, in the caseillustrated in FIG. 4A(iii), the average of the maximum values ofsegment lengths of the anode 140A in the various bending directions isremarkably decreased compared with the case illustrated in FIG. 4A(i).Therefore, as illustrated in an organic light emitting display deviceaccording to various exemplary embodiments of the present disclosure, ifan anode includes a first anode in a diamond shape and a second anodespaced apart from the first anode so as to surround the first anode, thepossibility of the occurrence of cracks caused by bending can beremarkably reduced as compared with a rectangular pixel area structurewidely used in the present time.

Referring to Table 1, in both cases illustrated in FIG. 4a (iii) andFIG. 4A(iv), the anode in a diamond shape positioned in a centralportion is not divided, so that the maximum values of segment lengths ofthe anode in angular directions and the average thereof are the same inthe cases illustrated in FIG. 4a (iii) and FIG. 4A(iv), and inparticular, the maximum value of a segment length of the anode in anangular direction of 0 degree is the same. In the case illustrated inFIG. 4a (iv), a corner portion of the anode where a force caused bybending in a direction of 0 degree can be divided, and, thus, an areawhere the force caused by bending in the direction of 0 degree isconcentrated can be eliminated, and the possibility of occurrence ofcracks caused by bending in the direction of 0 degree can be reduced ascompared with the case illustrated in FIG. 4A(iii).

The maximum values of segment lengths of the anodes illustrated in FIGS.4B (i), (ii), (iii), and (iv) in angular directions of 0 degree, 45degrees, and 90 degrees, and the average thereof were calculated.Details are as follows.

TABLE 2 Angle (based on X-axis) (i) (ii) (iii) (iv) 0 1 1.414 0.2320.232 45 1.414 1.333 0.657 0.657 90 2 2.828 0.465 0.465 Average 1.4711.858 0.451 0.451

As illustrated in Table 2, in the cases illustrated in FIGS. 4B (iii)and (iv), the number of sub-anodes constituting the anode having thesame area is greater than the number of the cases illustrated in FIGS.4A (iii) and (iv), and, thus, it can be seen that the average of themaximum values of segment lengths of the anode in the various bendingdirections is decreased as compared with the cases illustrated in FIGS.4A (iii) and (iv). Further, in the case illustrated in FIG. 4B(iv), acorner portion of the anode where a force caused by bending in adirection of 0 degree can be divided, and, thus, the possibility of theoccurrence of cracks caused by bending in the direction of 0 degree canbe reduced as compared with the case illustrated in FIG. 4B(iii).

FIG. 5A is a schematic plane view illustrating a light emitting areaemployed in an organic light emitting display device according to oneembodiment. In FIG. 5A, among various elements of an organic lightemitting display device, only light emitting areas 581A, 582A, and 583Aof an organic light emitting element 580A are illustrated forconvenience of explanation.

The organic light emitting element 580A includes a first light emittingarea 581A, a second light emitting area 582A, and a third light emittingarea 583A. The first light emitting area 581A has a diamond shape, thesecond light emitting area 582A is spaced apart from the first lightemitting area 581A so as to surround the first light emitting area 581A,and the third light emitting area 583A is spaced apart from the secondlight emitting area 582A so as to surround the second light emittingarea 582A. Although the shapes of the light emitting areas are, orotherwise oriented, in a diamond shape in reference to the bendingdirection, the shapes of each light emitting area is not particularlylimited as shown in FIG. 5A. Each of the light emitting areas may beanother polygonal shape or a circular shape.

Each of the first light emitting area 581A, the second light emittingarea 582A, and the third light emitting area 583A emits any one of red,green, blue colored light or white light. In some embodiments, the lightemitted from the first light emitting area 581A, the second lightemitting area 582A and the third light emitting area 583A may be of thesame spectral color or may be the white light. Alternatively, in someembodiments, at least one of the light emitting areas of the three lightemitting areas may be configured to emit light that is different fromthe light emitted from the other light emitting areas. In someembodiments, the first light emitting area 581A, the second lightemitting area 582A and the third light emitting area 583A maycollectively serve as a single sub-pixel area. Alternatively, in someembodiments, each of the first light emitting area 581A, the secondlight emitting area 582A and the third light emitting area 583A can bedefined as an individual sub-pixel area.

FIG. 5B is a cross-sectional view taken along a line Vb-Vb′ of FIG. 5Ato explain a driving method of the organic light emitting display deviceaccording to one embodiment. Referring to FIG. 5B, an organic lightemitting display device 500B includes a flexible substrate 510B, abuffer layer 531B, a thin-film transistor 520B, a gate insulating layer532B, an interlayer insulating layer 533B, an overcoating layer 534B,contact portions 529B and 529B′, an anode 540B, an organic lightemitting layer 550B, a cathode 560B, and a bank layer 570B according toone embodiment. The organic light emitting display device 500Billustrated in FIG. 5B is different from the organic light emittingdisplay device 100B illustrated in FIG. 1B in that the anode 540Bincludes a first anode 541B, a second anode 542B, and a third anode543B, and the number of the contact portions 529B and 529B′ are two in apixel. As for the flexible substrate 510B, the entire area of theflexible substrate 510B may be a bending area, or a partial area of theflexible substrate 510B may be a bending area. Although FIG. 5Aillustrates a direction in which the flexible substrate 510B is bent asa unit vector (1, 0), a direction in which the flexible substrate 510Bis bent as illustrated in FIG. 5B is one example of various directionsin which the flexible substrate 510B can be bent. A first light emittingarea 581B, a second light emitting area 582B, and a third light emittingarea 583B of the organic light emitting element 580B are arranged in thebending area of the flexible substrate 510B.

The organic light emitting element 580B including the anode 540B, theorganic light emitting layer 550B, and the cathode 560B is formed on theovercoating layer 534B. The organic light emitting element 580B includesthe first light emitting area 581B defined by the first anode 541B, afirst organic light emitting layer 551B and the cathode 560B, the secondlight emitting area 582B defined by the second anode 542B, a secondorganic light emitting layer 552B and the cathode 560B, and the thirdlight emitting area 583B defined by the third anode 543B, a thirdorganic light emitting layer 553B and the cathode 560B. The firstorganic light emitting layer 551B, the second organic light emittinglayer 552B, and the third organic light emitting layer 553B are organiclight emitting layers that emit any one of red, green, blue, and whitelight. The cathode 560B is formed on the organic light emitting layer550B. The cathode 560B may not be patterned and may be formed ascontinuous layer on the first organic light emitting layer 551B, thesecond organic light emitting layer 552B, and the third organic lightemitting layer 553B.

The bank layer 570B is formed on the overcoating layer 534B and theanode 540B. The bank layer 570B partitions the first anode 541B, thesecond anode 542B, and the third anode 543B. A first bank layer 571B ispositioned between the first anode 541B and the second anode 542B, asecond bank layer 572B is positioned between the second anode 542B andthe third anode 543B, and a third bank layer 573B is positioned at anend of the third anode 543B. Therefore, the first light emitting area581B, the second light emitting area 582B, and the third light emittingarea 583B are defined by the bank layer 570B.

Referring to FIG. 5B, the thin-film transistor 520B connected with thethird anode 543B is formed on the buffer layer 531B. The contact portion529B′ connected with the first anode 541B and the contact portion 529Bconnected with the second anode 542B are electrically connected with thethin-film transistor 520B on the interlayer insulating layer 553B.Therefore, the first light emitting area 581B, the second light emittingarea 582B, and the third light emitting area 583B are driven at the sametime. If the light emitting areas 581B, 582B, and 583B of the organiclight emitting element 580B can be driven at the same time, forming thelight emitting areas 581B, 582B, and 583B to emit the same color oflight is used for driving than forming the light emitting areas 581B,582B, and 583B to emit different colors of light.

Although FIG. 5B illustrates the thin-film transistor 520B connectedwith the third anode 543B, and the contact portions 529B′ and 529Bconnected with the first anode 541B and the second anode 542B,respectively, only the thin-film transistor 520B connected with thethird anode 543B may be formed. Further, the first anode 541B and thesecond anode 542B, and the second anode 542B and the third anode 543Bmay be connected with each other through a bridge electrode.

In the organic light emitting display device 500B according to oneembodiment, the first organic light emitting layer 551B, the secondorganic light emitting layer 552B, and the third organic light emittinglayer 553B may emit the same color of light such as a red, green, blue,or white light. If the first organic light emitting layer 551B, thesecond organic light emitting layer 552B, and the third organic lightemitting layer 553B emit white light, the first organic light emittinglayer 551B, the second organic light emitting layer 552B, and the thirdorganic light emitting layer 553B can be connected with each other.

If the first organic light emitting layer 551B, the second organic lightemitting layer 552B, and the third organic light emitting layer 553B areorganic light emitting layers that may emit light within a certainlimited range of wavelengths or white light, a color filter may be usedtogether. The color filter may be formed above or under the firstorganic light emitting layer 551B, the second organic light emittinglayer 552B, and the third organic light emitting layer 553B and convertsthe white light emitted from the first organic light emitting layer551B, the second organic light emitting layer 552B, and the thirdorganic light emitting layer 553B into different colors of light such asred light, blue light, or green light. A light emitting area withoutusing a color filter serves as a white sub-pixel area.

If a color filter is used, the color filter may include a red colorfilter, a green color filter, and a blue color filter, which may bearranged so as to correspond to the first light emitting area 581B, thesecond light emitting area 582B, and the third light emitting area 583B,respectively. In some embodiments, one color filter may be formed so asto correspond to the multiple light emitting areas 581B, 582B, and 583B.For example, the red color filter may be formed so as to correspond tothe first light emitting area 581B and the second light emitting area582B, and the blue color filter may be formed so as to correspond to thethird light emitting area 583B. As such, the color filters may be formedso as to correspond to the light emitting areas 581B, 582B, and 583B invarious ways.

FIG. 5C is a cross-sectional view taken along the line Vb-Vb′ of FIG. 5Ato explain another driving method of an organic light emitting displaydevice according to one embodiment. Referring to FIG. 5C, an organiclight emitting display device 500C includes a flexible substrate 510C, abuffer layer 531C, thin-film transistors 520C, 520C′, and 520C″, a gateinsulating layer 532C, an interlayer insulating layer 533C, anovercoating layer 534C, an anode 540C, an organic light emitting layer550C, a cathode 560C, and a bank layer 570C according to one embodiment.The organic light emitting display device 500C of FIG. 5C is differentfrom the organic light emitting display device 500B illustrated in FIG.5B only that a discrete thin-film transistors 520C′, 520C′ and 520C″ areemployed in a pixel.

The thin-film transistors 520C″, 520C′, 520C corresponding to a firstanode 541C, a second anode 542C, and a third anode 543C are formed onthe buffer layer 531C. The first anode 541C, the second anode 542C, andthe third anode 543C are electrically connected with source electrodes523C″, 523C′, and 523C of the thin-film transistors 520C″, 520C′, 520C,respectively. Therefore, the first anode 541C, the second anode 542C,and the third anode 543C may be applied with different voltages from thethin-film transistors 520C″, 520C′, 520C, respectively.

Since the first anode 541C, the second anode 542C, and the third anode543C may be applied with different voltages, a first light emitting area581C, a second light emitting area 582C, and a third light emitting area583C can be driven independently from each other. In this case, a colorof light emitted from a first organic light emitting layer 551C, a colorof light emitted from a second organic light emitting layer 552C, and acolor of light emitted from a third organic light emitting layer 553Ccan emit different color of light so that each light emitting area serveas an individual sub-pixel area. Therefore, in the organic lightemitting display device 500C according o of the present disclosure,sub-pixel areas can be arranged and applied in various ways as comparedwith the organic light emitting display device 500B designed tosimultaneously drive the light emitting areas.

Each of the first organic light emitting layer 551C, the second organiclight emitting layer 552C, and the third organic light emitting layer553C may be one of a red organic light emitting layer, a green organiclight emitting layer, and a blue organic light emitting layer. Inparticular, the third organic light emitting layer 553C formed in thethird light emitting area 583C may be a blue organic light emittinglayer. Generally, among a red organic light emitting layer, a greenorganic light emitting layer, and a blue organic light emitting layer,the blue organic light emitting layer has the lowest light emittingefficiency. Therefore, among a red sub-pixel area, a green sub-pixelarea, and a blue sub-pixel area constituting a pixel area, the bluesub-pixel area may be set to be relatively bigger so as to be preferablein terms of a life of an organic light emitting element and powerconsumption. In the organic light emitting display device 500C accordingto one embodiment, the third light emitting area 583C is formed at theoutermost portion, so that the third light emitting area 583C has thegreatest area as compared with the other light emitting areas.Therefore, the third organic light emitting layer 553C formed in thethird light emitting area 583C having the greatest area also has thegreatest area as compared with the other organic light emitting layers.Thus, the third organic light emitting layer 553C may be formed as ablue organic light emitting layer.

Although FIG. 5C illustrates that the organic light emitting displaydevice 500C includes the three thin-film transistors 520C″, 520C′, 520C,the organic light emitting display device 500C may include two thin-filmtransistors. For example, each of the second anode 542C and the thirdanode 543C may be electrically connected with the thin-film transistors520C′ and 520C, respectively. And the first anode 541C may beelectrically connected with the thin-film transistor 520C or thethin-film transistor 520C′ through a contact portion connected with thefirst anode 541C. Since each of the second anode 542C and the thirdanode 543C is electrically connected with the thin-film transistors520C′ and 520C, respectively, the second light emitting area 582B andthe third light emitting area 583B may be independently driven. If thecontact portion is connected with the thin-film transistor 520C′, thefirst light emitting area 581C and the second light emitting area 582Care driven at the same time, and if the contact portion is connectedwith the thin-film transistor 520C, the first light emitting area 581Cand the third light emitting area 583C can be driven at the same time.

Although FIG. 5B and FIG. 5C define organic light emitting elements 580Band 580C as having three light emitting areas, the present disclosure isnot limited thereto. The organic light emitting elements 580B and 580Ccan be defined as having multiple light emitting areas.

The organic light emitting display devices 580B and 580C according tothe embodiments herein may be organic light emitting display devicesbent in a certain direction. In this case, at least one of the firstlight emitting area 581B, the second light emitting area 582B, and thethird light emitting area 583B may be divided in a directionperpendicular to a bending direction of the flexible substrate 510B. Ifa shape of a light emitting area is the same as a shape of an anode, asegment length of the anode 540B in the bending direction can bereduced.

In the organic light emitting display devices 500B and 500C according tovarious embodiments herein, each of the organic light emitting elements580B and 580C includes multiple light emitting areas and one of themultiple light emitting areas is spaced apart from the other lightemitting area so as to surround the outermost portion of the other lightemitting area. Further, the multiple light emitting areas of the organiclight emitting elements 580B and 580C are arranged in the bending areasof the flexible substrates 510B and 510C. Therefore, in the organiclight emitting display devices 500B and 500C according to variousembodiments herein, shapes of the anodes 540B and 540C may be formed soas to correspond to shapes of the light emitting areas of the organiclight emitting elements 580B and 580C. Thus, segment lengths of theanodes 540B and 540C in bending directions of the bending areas of theflexible substrates 510B and 510C can be reduced, and the possibility ofoccurrence of cracks in the anodes 540B and 540C can be reduced.

FIG. 6 is a flowchart provided for explaining a method for reducing aforce received by an organic light emitting element due to bending ofthe organic light emitting element according to one embodiment. FIG. 7Ato FIG. 7C are cross-sectional views of respective processes providedfor explaining the method for reducing a force received by an organiclight emitting element due to bending according to one embodiment.

Firstly, on a flexible substrate 710, thin-film transistors 720, 720′,and 720″ are formed (S60), an anode material layer 790 is patterned soas to form a first anode 741, a second anode 742 spaced apart from thefirst anode 741 on the same plane level with the first anode 741 so asto surround the first anode 741, and a third anode 743 spaced apart fromthe second anode 742 on the same plane with the second anode 742 so asto surround the second anode 742 on the thin-film transistors 720, 720′,and 720″ at the same time. Forming the thin-film transistors 720, 720′,and 720″ and then forming the first anode 741, the second anode 742, andthe third anode 743 will be explained in more detail with reference toFIG. 7A and FIG. 7B.

Referring to FIG. 7A, the flexible substrate 710 for supporting variouselements of an organic light emitting display device 700 is used. Theflexible substrate 710 is formed of a material selected from the groupconsisting of a polyester-based polymer, a silicon-based polymer, anacryl-based polymer, a polyolefin-based polymer, and combinationsthereof. Such materials can be bent such that the organic light emittingdisplay device 700 serves as a flexible display device.

A buffer layer 731 is formed on the flexible substrate 710. The bufferlayer 731 prevents permeation of moisture or impurities through theflexible substrate 710 and planarizes an upper part of the flexiblesubstrate 710. Although FIG. 7A illustrates that the buffer layer 731 isformed, the buffer layer 731 may not be formed based on a kind of thethin-film transistors 720, 720′, and 720″ used in the organic lightemitting display device 700. As illustrated in FIG. 7A, if the bufferlayer 731 is formed, the buffer layer 731 may be formed of a siliconoxide film, a silicon nitride film, or a dual layer thereof.

Active layers 721, 721′, and 721″ are formed on the buffer layer 731.The active layers 721, 721′, and 721″ may be formed of any one ofamorphous silicon, polycrystalline silicon, or an oxide semiconductor.On each of the active layers 721, 721′, and 721″, a gate insulatinglayer 732 may be formed of a silicon oxide film, a silicon nitride film,or a dual layer thereof. On the gate insulating layer 732, each of gateelectrodes 722, 722′, and 722″ may be formed of any one selected fromthe group consisting of molybdenum (Mo), aluminum (Al), chromium (Cr),gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu),two or more alloys, or two or more layers. An interlayer insulatinglayer 733 is formed of the same material as the gate insulating layer732 on each of the gate electrodes 722, 722′, and 722″. Sourceelectrodes 723, 723′, and 723″ and drain electrodes 724, 724′, and 724″are formed on the interlayer insulating layer 733 so as to be in contactwith the active layers 721, 721′, and 721″, respectively. The sourceelectrodes 723, 723′, and 723″ and the drain electrodes 724, 724′, and724″ may be formed of any one selected from the group consisting ofmolybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti),nickel (Ni), neodymium (Nd), and copper (Cu), two or more alloys, or twoor more layers, but they do not need to formed of the same material asthe gate electrodes 722, 722′, and 722″.

As described above, the thin-film transistors 720, 720′, and 720″including the active layers 721, 721′, and 721″, the gate electrodes722, 722′, and 722″, the source electrodes 723, 723′, and 723″, and thedrain electrodes 724, 724′, and 724″, respectively, are formed, and,then, an overcoating layer 734 is formed on each of the thin-filmtransistors 720, 720′, and 720″. The overcoating layer 734 may be formedof one or more materials of an acryl-based resin, an epoxy resin, aphenol resin, a polyamide-based resin, a polyimide-based resin, anunsaturated polyester-based resin, a polyphenylene-based resin, apolyphenylene sulfide-based resin, and benzocyclobutene. After theovercoating layer 734 is formed, contact holes are formed in theovercoating layer 734 such that a part of each of the source electrodes723, 723′, and 723″ in the thin-film transistors 720, 720′, and 720″ canbe exposed.

After the overcoating layer 734 is formed, the anode material layer 790is formed on the overcoating layer 734 (S61). The anode material layer790 includes a reflective layer as a conductive layer having a highreflectivity and a transparent conducive layer formed of a transparentconductive oxide having a high work function on the reflective layer.

Referring to FIG. 7A and FIG. 7B, after the anode material layer 790 isformed, the anode material layer 790 is patterned. By patterning theanode material layer 790, the first anode 741, the second anode 742spaced apart from the first anode 741 on the same plane with the firstanode 741 so as to surround the first anode 741, and the third anode 743spaced apart from the second anode 742 on the same plane with the secondanode 742 so as to surround the second anode 742 are formed at the sametime (S62). That is, on the anode material layer 790 formed on theentire surface of the overcoating layer 734, only the anode materiallayer 790 in areas corresponding to the first anode 741, the secondanode 742, and the third anode 743 remains through a photoresist processor the like, and the anode material layer 790 in the other areas iseliminated, so that the first anode 741, the second anode 742, and thethird anode 743 are formed at the same time.

Additionally, at least one of the first anode 741, the second anode 742,and the third anode 743 maybe formed into multiple patterns. Inparticular, if an organic light emitting element of a bent organic lightemitting display device is positioned in a bending area, the first anode741, the second anode 742, and the third anode 743 may be formed in adirection perpendicular to the bending direction of the organic lightemitting display device. By patterning the first anode 741, the secondanode 742, and the third anode 743 in separate forms, a strain on thefirst anode 741, the second anode 742, and the third anode 743 due tobending of an anode 740 can be reduced.

Although FIG. 7B illustrates that the first anode 741, the second anode742, and the third anode 743 are electrically connected with thethin-film transistors 720, 720′, and 720″, respectively, only one or twothin-film transistors may be used. In this case, a first bridgeelectrode connecting the first anode 741 and the second anode 742 or/anda second bridge electrode connecting the second anode 742 and the thirdanode 743 may be formed. The first bridge electrode and the secondbridge electrode may be formed at the same time when the first anode741, the second anode 742, and the third anode 743 are formed. Further,if only one thin-film transistor is used or only two thin-filmtransistors are used, among the first anode 741, the second anode 742,and the third anode 743, any anode which is not in direct contact withthe thin-film transistor can be electrically connected with thethin-film transistor while being in contact with a contact portionelectrically connected with the thin-film transistor.

Then, on each of the first anode 741, the second anode 742, and thethird anode 743, an organic light emitting layer 750 is formed (S63),and on the organic light emitting layer 750, a cathode 760 is formed(S64). Forming the organic light emitting layer 750 and then forming thecathode 760 will be explained in more detail with reference to FIG. 7C.

Referring to FIG. 7C, a bank layer 770 that opens a part of the anode740 is formed on the anode 740. The bank layer 770 may be formed of anyone of organic insulating materials and may be formed using, forexample, a positive-type photoresist.

On the anode 740 opened by the bank layer 770, the organic lightemitting layer 750 is formed. On the first anode 741 opened by a firstbank layer 771, a first organic light emitting layer 751 is formed; onthe second anode 742 opened by the first bank layer 771 and a secondbank layer 772, a second organic light emitting layer 752 is formed; andon the third anode 743 opened by the second bank layer 772 and a thirdbank layer 773G, a third organic light emitting layer 753 is formed.Therefore, the first organic light emitting layer 751 may have the sameshape as the first anode 741; the second organic light emitting layer752 may have the same shape as the second anode 742; and the thirdorganic light emitting layer 753 may have the same shape as the thirdanode 743.

Although FIG. 7C illustrates that the first organic light emitting layer751, the second organic light emitting layer 752, and the third organiclight emitting layer 753 are formed in separate forms, the first organiclight emitting layer 751, the second organic light emitting layer 752,and the third organic light emitting layer 753 may be connected witheach other and formed into the single organic light emitting layer 750by depositing an organic light emitting material on the entire surface.In this case, the organic light emitting layer 750 may be an organiclight emitting layer that emits white light.

On the organic light emitting layer 750, the cathode 760 is formed. Thecathode 760 is formed of a metallic material having a low work functionand may be formed of a metallic material such as silver (Ag), titanium(Ti), aluminum (Al), molybdenum (Mo), or an alloy of silver (Ag) andmagnesium (Mg). Further, the cathode 760 may be formed of carbon nanotube and graphene. In order to form the substantially transparentcathode 760, the cathode may be formed to a thickness of several hundredangstrom (Å) or less, for example, 200 Å or less.

An organic light emitting layer 780 includes a first light emitting area781 defined by the first anode 741, the first organic light emittinglayer 751, and the cathode 760, a second light emitting area 782 definedby the second anode 742, the second organic light emitting layer 752,and the cathode 760, and a third light emitting area 783 defined by thethird anode 743, the third organic light emitting layer 753, and thecathode 760.

The present invention has been described in more detail with referenceto the exemplary embodiments, but the present invention is not limitedto the exemplary embodiments. It will be apparent to those skilled inthe art that various modifications can be made without departing fromthe technical principle of the invention. Accordingly, the exemplaryembodiments disclosed in the present invention are used not to limit butto describe the technical principle of the present invention, and thetechnical principle of the present invention is not limited to theexemplary embodiments. Therefore, the exemplary embodiments describedabove are considered in all respects to be illustrative and notrestrictive. The protection scope of the present invention must beinterpreted by the appended claims and it should be interpreted that alltechnical principles within a scope equivalent thereto are included inthe appended claims of the present invention.

What is claimed is:
 1. A flexible organic light emitting display devicehaving a plurality of pixels, at least one of the pixels comprising: atleast one thin-film transistor; a first anode on the thin-filmtransistor; a second anode on the thin-film transistor, the second anodespaced apart from the first anode and surrounding the first anode; anorganic light emitting layer on the first anode and the second anode;and a cathode on the organic light emitting layer.
 2. The flexibleorganic light emitting display device according to claim 1, wherein ashape of the second anode corresponds to a shape of the first anode. 3.The flexible organic light emitting display device according to claim 2,wherein the first anode has a rectangular shape.
 4. The flexible organiclight emitting display device according to claim 3, wherein corners ofthe first anode and the second anode are rounded.
 5. The flexibleorganic light emitting display device according to claim 1, wherein theone pixel includes at least one thin-film transistor that is connectedto both the first anode and the second anode.
 6. The flexible organiclight emitting display device according to claim 1, wherein each of thefirst anode and the second anode of the pixel are connected to adiscrete thin-film transistor.
 7. The flexible organic light emittingdisplay device according to claim 1, further comprising: a bridgeelectrode that connects the first anode and the second anode.
 8. Theflexible organic light emitting display device according to claim 1,wherein at least one of the first anode and the second anode has adivision gap formed therein in a direction perpendicular to a bendingdirection of a flexible substrate.
 9. A flexible organic light emittingdisplay device comprising: a first anode configured to have a certainshape; and a second anode configured to encompass the first anode, thesecond anode having substantially the same shape as the certain shapeand spaced apart from the first anode, wherein such encompassedconfiguration of the first anode and the second anode accommodatesbending stress with respect to the first anode and the second anodebeing implemented in an organic light emitting display device that isbendable, rollable, foldable or otherwise flexible.
 10. The deviceaccording to claim 9, wherein the first anode and the second anode areon the same plane with a diamond-like configuration.
 11. The deviceaccording to claim 10, wherein at least one among the first anode andthe second anode has at least one segment length therein.
 12. The deviceaccording to claim 11, further comprising a third anode being a part ofthe substantially the same diamond-like configuration of the first anodeand the second anode.
 13. The device according to claim 11, wherein oneor more corners of at least one among the first anode and the secondanode are rounded.
 14. The device according to claim 13, wherein atleast one among the first anode, the second anode, and third anode areformed of a transparent conductive material having one among atransparent conductive oxide (TCO), an indium tin oxide (ITO), an indiumzinc oxide (IZO), an indium tin zinc oxide (ITZO), a zinc oxide, and atin oxide.
 15. The device according to claim 10, further comprising anorganic light emitting layer for one or more sub-pixels, with a lightemitting area of each sub-pixel having a diamond-like configurationsimilar to or the same as that of the first anode or the second anode.16. The device according to claim 15, further comprising a bank layerbetween two adjacent light emitting areas.
 17. The device according toclaim 16, further comprising at least one thin-film transistor connectedto the at least one among the first anode and the second anode.
 18. Thedevice according to claim 17, wherein the first anode and the secondanode are connected together via a bridge electrode.
 19. The deviceaccording to claim 15, further comprising a cathode over the organiclight emitting layer and a color filter layer over or under the organiclight emitting layer.
 20. The device according to claim 15, furthercomprising a cathode over the organic light emitting layer and the oneor more sub-pixels, with each sub-pixel configured to emit one amongred, green, blue, or white light.